1. Field of the Invention
The present invention is related to an electrical socket connector, and more particularly to a zero insertion force (ZIF) socket connector for connecting a central processing unit (CPU) to a printed circuit board.
2. Description of Related Art
ZIF socket connectors are popularly used in computer industry for electrically connecting CPUs with printed circuit boards (PCBs). U.S. Pat. Nos. 5,489,218, 5,679,020, 5,722,848, 6,371,786 and 6,383,006 all disclose conventional ZIF socket connectors. These ZIF socket connectors each comprise a base having a number of contact passageways retaining conductive terminals therein, a cover slidably engaging with the base and defining a corresponding plurality of pin holes for receiving contact pins of a CPU therein, and a driving device sandwiched between the cover and the base for driving the cover to move relative to the base. When the CPU is mounted on the cover, the pins thereof are received in the respective pin holes of the cover.
Following the increasing functions of the CPU, the number of the contact pins thereof increases accordingly. For advanced CPU such as Intel Northwood or AMD SledgeHammer, vibration of the CPU mounted on a socket connector due to an operation of a cooling fan becomes a problem. To solve this problem, a standoff is formed on periphery edges of a top face of the cover of the socket connector, so that top enlarged ends of the pins will not engage with the top face of the cover of the socket, as shown in FIG. 5 of the present application. FIG. 5, in a cross-sectional manner, shows a related ZIF socket connector 7 for electrically connecting a CPU 8 with a printed circuit board 92. The socket connector 7 has a cover 70 slidably mounted on a base 73 thereof. A standoff 72 is formed on periphery edges of a top face of the cover 70. A plurality of contacts 74 is received in the base 73. The CPU 8 is mounted on the top face of the cover 70 and supported by the standoff 72. The CPU 8 has pins 81 extending downwardly through pin holes 71 defined in the cover 70 into the base 73 to electrically connect with the contacts 74. Each pin 81 has an enlarged top end 811 received in a recess 75 in the top face within the standoff 72. A heat sink 9 is mounted on the CPU 8. A cooling fan (not shown) is mounted on the heat sink 9. A clamping force F is applied to the heat sink 9 to cause it to have an intimate engagement with the CPU 8 so heat generated by the CPU 8 can be effectively dissipated by the heat sink 9. Although the socket connector 7 can resolve the problem of vibration of the CPU 8 due to an operation of the cooling fan, since there lacks any support other than the standoff 72, the clamping force F causes the CPU to have an excessive deflection about its central portion, which may result in damage of the CPU 8.
Hence, it is requisite to provide an improved electrical socket connector to overcome the above-mentioned disadvantages of the prior art.
Accordingly, an object of the present invention is to provide a ZIF socket connector which can overcome the problem of vibration of CPU mounted on the socket connector due to an operation of a cooling fan and at the same time provides support to the CPU to prevent it from excessive deformation due to a clamping force for firmly fastening a heat sink to the CPU.
In order to achieve the object set forth, a ZIF socket connector in accordance with the present invention is used for electrically connecting a CPU with a circuit board. The socket connector comprises a base defining an array of terminal cells, a plurality of conductive contacts received in the respective terminal cells, a cover slidably mounted on the base and a driving device sandwiched between the cover and the base for driving the cover to move relative to the base. The cover defines an array of pin holes corresponding to the terminal cells and communicating therewith for insertion of pins of the CPU therethrough, and has a supporting surface for supporting the CPU. A standoff is formed on each of peripheral edges of the supporting surface and a plurality of supporting posts is formed on the supporting surface within the outline positions of the standoffs for supporting the CPU mounted on the socket connector in accordance with the present invention. The standoff and the supporting posts have the same height.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.